解決SpringBoot啟動提示：is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)

發現SpringBoot啟動時，列印了這樣的日志：

2021-10-13 17:20:47.549 [main] INFO  ... Bean 'xxx' of type [xxx] 
is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)      

這是由于某一個service實作了BeanPostProcessor接口，同時這個Service又依賴其他的Service導緻的。例子如下：

@Service
public class RandomIntProcessor implements BeanPostProcessor {

    @Autowired
    private RandomIntGenerator randomIntGenerator;

    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        Field[] fields = bean.getClass().getDeclaredFields();
        for (Field field : fields) {
            RandomInt injectRandomInt = field.getAnnotation(RandomInt.class);
            if (injectRandomInt != null) {
                int min = injectRandomInt.min();
                int max = injectRandomInt.max();
                int randomValue = randomIntGenerator.generate(min, max);
                field.setAccessible(true);
                ReflectionUtils.setField(field, bean, randomValue);
            }
        }
        return bean;
    }
}      

其中RandomIntProcessor類依賴了RandomIntGenerator類，會導緻RandomIntProcessor.postProcessBeforeInitialization方法無法接收到RandomIntGenerator初始化事件。

可修改為如下：

@Service
public class RandomIntProcessor implements BeanPostProcessor {
private final RandomIntGenerator randomIntGenerator;

    @Lazy
    public RandomIntProcessor(RandomIntGenerator randomIntGenerator) {
        this.randomIntGenerator = randomIntGenerator;
    }

    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        //...
    }
}      

使用Lazy注解延遲初始化，打破循環依賴關系。